Aplysia californica has been one of the dominant invertebrate model organisms utilized for research on the neurobiology of behavior, learning, and long-term memory. A key finding in recent studies is that both the functional and structural changes for memory storage are synapse-specific and require local translation. To understand the molecular mechanisms underlying long-term memory storage including its structural underpinning, it will be essential to determine how the population of mRNAs is destined for translation in synapses during memory formation. To examine this issue, we will extract mRNAs from kinesin transport complexes from ganglia and cultured individual sensory and motor neurons following treatment with the neurotransmitter serotonin (involved in learning-related long-term facilitation) and with FMRFamide (involved in long-term inhibition). At several time points after treatment, we will also characterize the mRNAs being actively translated on free and membrane-bound polysomes. The latter should include proteins targeted to the synaptic vesicles and membranes. Isolated mRNAs from all 3 populations (kinesin complexes, free polysomes, bound polysomes) will be hybridized to an Aplysia cDNA microarray containing features specific for the majority of central nervous system (CNS) genes. This microarray, an expansion of our current array, will be constructed from the unique clones in the EST libraries we have already generated from individual neurons, pedal-pleural ganglia, and the whole CNS of Aplysia. While we estimate these clones cover nearly 80% of all genes expressed in Aplysia neurons, only a fraction of the library has been annotated due to insufficient coding information. Nearly full annotation of the libraries will be achieved by sequencing full-length cDNAs from the same CNS sources. The full-length cDNA libraries and the Aplysia microarray will provide important resources for investigators to study learning and other behavior paradigms in this important model organism.